Drought stress in vineyards

Mid-summer drought conditions in a local Niagara vineyard can present problems not only with the vines, but also with cover crop establishment below the vines (photo: Heather VanVolkenburg).

Nowadays, we have to face the reality of climate change. In the Niagara Region, heat waves and extended dry periods are projected to become more frequent during the growing season (July to August). Like almost all agricultural activities, viticulture (grape growing) is highly dependent on climatic conditions, meaning that such changes are increasingly making vineyard management more challenging. Drought conditions can ultimately lead to economic losses due to decreases in production and/or wine quality, for example, and understanding how vineyard managers have learned to adapt to extreme periods of drought will help to support a more sustainable system overall.

Droughts are defined as a combination of both high temperatures and a lack of water. Extended periods of drought affect the vineyard in many ways. First, it can negatively affect the grapes’ yield by inhibiting the amount of plant photosynthesis, leading to reduced berry development if the decrease occurs early in the growing season. In addition, heat waves can drastically decrease the number of berries and clusters formed. Extended temperatures above 30°C may also result in pauses in the vine’s ability to acquire nutrients from the soil. If this happens, wine produced from those grapes may end up with high alcohol and pH levels that leave them unbalanced or “flabby.” This results in an increased risk of spoilage as well as wines with poor colour and aroma profiles. Extended dry periods may also result in changes to the soil structure — making the soil hard and clumpy, especially in clay soils ­— thus becoming more difficult to manage. Dry soil is also more prone to wind erosion due to its dusty texture.

One of the less obvious challenges linked to drought stress is that stressed grapevines tend to attract more grape pest species. A stressed plant will have a weakened immune system, making it incapable of properly defending itself against pest attacks. Spider mites are one such species that may increase in abundance during dry periods, potentially inflicting further damage to the already stressed vines. How moisture, or lack thereof, in the vineyard is managed matters, and it is crucial for growers to understand the balance between not having enough and having too much.

To continue the production of high-quality wines at economically accepted yields in a dryer and warmer climate, growers need to apply adaptive strategies. The choice of vine cultivars, rootstocks and adequate training systems are crucial for drought adaptation. In addition, combining other management techniques such as cover cropping and irrigation can help vineyards adapt to extreme drought conditions. Understanding how different drought management techniques work together is one of the key elements in our research and our work is to help farmers choose the best combination of management techniques that will optimize the sustainability of production at the local scale.

This blog will be ongoing throughout the duration of the project with bi-weekly updates provided by Liette Vasseur, Heather VanVolkenburg, Kasia Zgurzynski, Habib Ben Kalifa, and Diana Tosato (see research team). We will be providing research activity updates as well as informative pieces that delve into agricultural concepts and important global issues as they relate to agricultural sustainability and climate change. Stay tuned for regular updates!


Categories: Organic Science Cluster 3 Blog